The Journal of Mountain Medicine and Ecology

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Volume 2 No. 1 Spring 2010

The Journal of Mountain Medicine and Ecology unites the sciences of Medicine and Ecology in a peer reviewed format of original contributions, review articles, commentaries, and abstracts of original research. The journals focus calls attention to Human induced environmental changes which impact public health.

Editor: Robert W. Derlet, UC Davis [email protected]

Assistant Editor: John R. Richards, UC Davis [email protected]

Editorial Board: Carling Ursem, Columbia University, New York, NY, USA

K. A. Ger, Federal University do Rio Grande do Norte, Brazil

Printed and distributed at Davis, CA 95616 USA J. Mountain Medicine and Ecology Periphyton along the JMT

Periphyton in Alpine Lakes and Streams along the John Muir Trail in the Sierra Nevada: Relationship to Human Impact

Curtis Hayden1, Robert W. Derlet, M.D.1,2,Charles R. Goldman, PhD.1,2

From the University of California, Davis. Davis , CA (1) and the John Muir Institute of the Environment. Davis, CA (2). Address correspondence to:Robert W. Derlet, M.D. UC Davis Med Center PSSB 2100: 4150VStreetSacramento, CA 95817. [email protected]

Abstract

OBJECTIVE: Within the Sierra Nevada, the 335 km (210 mile) John Muir Trail (JMT) attracts thousands of backpackers each year who complete either segments or the entire trail from Yosemite Valley to MT. Whitney. This report is a follow up study to a research project done during summer 2008 along the JMT which analyzed the risk of acquiring waterborne disease by determining prevalence and changes in coliform bacteria, and Escherichia coli (E. coli). The aim of the current study is to access the biomass of attached periphyton (attached algae) in the same lakes and streams and compare to indicator bacterial prevalence. METHODS: Water from 20 sites adjacent to the JMT and identical to the prior years study was analyzed. Water was collected on Millipore bacteria transport filters for coliform and E-coli, and transported to the lab for analysis. Chlorophyll-a was collected on glass fiber filters, preserved and transported. Attached algae biomass was measured using a modified California Dept of Fish and game method. Findings were correlated with environmental land use which might affect water quality. RESULTS: We analyzed surface water at 20 different sites in the summer of 2009. Coliforms prevalence was higher in Mixed-use sites (63%) compared with Backpack sites (28%), and Pristine sites (0%). Chlorophyll-a measurements were inconclusive. Periphyton biomass was highest at Mixed use sites, where mean maximum biomass readings were 59% compared to 42% at Backpack sites and 10% at Pristine sites (P<0.05). CONCLUSION: Our study provides confirmation for the findings of earlier studies, and presents evidence that lakes and stream impacted by pack and stock animal traffic have increased eutrophication levels compared to watersheds without pack animals. In addition higher levels of periphyton are associated with coliform presence.

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Introduction addition, organic carbon, nitrogen, Several remote trail systems have phosphorus and iron are added to an been constructed in the Sierra Nevada of otherwise oligotrophic environment by California that are popular with summer various human activities (Horne and backpackers. Most well known of these is Goldman, 1994). These nutrients stimulate the John Muir Trail (JMT) which serves as algae and aquatic growth, which in turn an internationally recognized high elevation provide a supportive environment for mountain trail that begins in Yosemite sustaining exogenous microorganisms, Valley and traverses through multiple which may have been introduced (Jasson et watersheds 335 km (210 miles) to the top of al., 2006). Furthermore, certain algae Mount Whitney at 4,418 m (14,495 ft) produce and secrete toxins, which are above sea level (Lowe and Lowe, 1982). It harmful and can be lethal to fish, wildlife, is one of the most popular and crowded long pets and humans. Introduction of algae distance mountain trails in the United States. toxins into domestic waters systems can be The northern portion of the trail is located catastrophic. within Yosemite National Park, the central portion between Yosemite and Kings Eutrophication of lakes and streams Canyon (123 km), and the southern portion is a complicated multistep process that within Kings Canyon and Sequoia National occurs over an extended time. One of the Parks (Wenk and Morey, 2007). Water can first effects of pollutants containing only be obtained from trailside or nearby phosphorus (P) or Nitrogen (N) is to lakes and streams, and backpackers stimulate growth of attached algae. Small commonly collect water for drinking several amounts of spot localized growth over time times each day. The purity of water along becomes confluent, and ultimately a flume the trail is important to increase the success extends progressively downstream. In lakes of completing the entire trail, as well to the and stagnant streams, increases in suspended health of each individual backer. In addition, algal species populations, such as diatoms the JMT crosses the headwaters of Reverse can greatly degrade water clarity. With time Creek, the Merced, Tuolumne, San Joaquin, and continuing nutrient support, blue green Kings and Kern Rivers watersheds that algae may have a competitive advantage and provide drinking water to the many water become dominant. The blue green algae, systems in California (Carle, 2004). once established are difficult to remove, and secrete harmful toxins. The high usage of the JMT and adjacent areas create a risk for Water in the Sierra, along the JMT is contamination by many different species of highly sensitive to eutrophication due to the microbes. Pathologic microorganisms such environmental and geographic features of as enterotoxic strains of Escherichia coli (E. the Sierra Nevada Mountains. The high coli), Salmonella, Giardia, or other harmful elevation portions of the watershed consists microorganisms may be introduced into of surface or subsurface granite and wilderness lakes and streams from visiting metamorphic rock, with little topsoil humans, pack and stock animals, and to a (Moore, 2000). Therefore total soil lesser extent by endogenous wildlife (Ursem adsorption and buffering capacity is low, 2009, Derlet et al, 2008, Atwill 2004). In providing minor or no biogeochemical

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retention or transformation of nutrients such of the JMT between Duck Creek just south as nitrogen (N) and phosphorus (P) (Horne of the Mammoth Lakes region, to the JMT and Goldman, 1994). Therefore relatively entrance of Kings Canyon National Park at small amounts of nutrient or microbial Piute Creek (2,438 m), as shown on figure 1. additions or habitat disturbances can lead to As a designated wilderness area, both significant impacts on nutrient flux and logging and motorized vehicle use are subsequently degrade water quality and prohibited within the John Muir Wilderness. aquatic ecosystems (Goldman, 2000). For In addition, wilderness permits are required example, sunscreen, soaps, detergents, skin for overnight use. John Muir Trail hikers oils, food particles, may be leach into lakes collect drinking water both from water and streams by passing through thin porous sources crossing the trail as well as nearby soil. Pack animal and Cattle manure may be off trail campsites. Therefore we sampled deposited directly into waterways, or be water at selected off trail sites, up to three swept into the water, instead of being km from the trail. Sampling sites were absorbed and fixed in deep soil. Snowmelt categorized into three different types based and precipitation, especially episodic on land usage and activity patterns that summer thunderstorms bring surface could impact the water quality. pollutants into creeks, lakes, and Classification categories and criteria are downstream reservoirs. described in the following table. A previous study conducted along the JMT in 2008 found that Coliforms and Sampling Site Classification Criteria E-coli prevalence were associated with watersheds trampled 1) mixed use areas defined as those watershed only by wildlife: rarely Wildlife/Pristine areas used both by packers and backpackers traversed by humans and (Ursem 2009). These increased temporally inaccessible to pack and over the summer. At mixed use sites, stock animals suspended algae as measured by 2) Backpack watersheds used lightly chlorophyll-a levels increased and were by backpackers and correlated with E-coli and Coliforms rarely by pack and stock prevalence. That study did not document the animal impact biomass of periphyton, which was observed watersheds traversed by but not quantified or recorded. The purpose 3) Mixed Use both humans and of this current study is to determine 1) the domesticated animals biomass of attached algae in lakes and

streams, and 2) to confirm the results of the 2008 study that measured coliform and E- At each sampling the sites were coli prevalence, and Chlorophyll-a levels. studied for evidence of humans and/or pack animal impact by inspecting campsites,

terrain changes, and residual manure. Table Methods 1 describes the 20 sites, with a specific description and location of each sampling Field site selection site. Site characteristics were also stratified during previous years with the assistance of Water was sampled from sites in the the United States Department of Agriculture John Muir Wilderness along a 72 km portion Forest Service. Some sites are officially

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recognized as geographic milestones and Laboratory Analysis therefore are not reported in metric units. Prevalence of coliforms and E. coli Field Sampling and Measurements from total bacterial counts was calculated following standardized laboratory Sites were studied during August procedures, and as described in a prior study 2009. Lakes were sampled at the outlet or as (American Public Health Association, 1998, close as possible to the outlet. When the Ursem 2009). In summary, the Millipore water source was a river or creek it was tubes were incubated at 35º C for 24 hours; sampled in the one most representative colonies were then counted and sub-plated location. A modified California Dept of Fish in duplicate onto sheep blood and and Game method of estimating attached MacConkey agar plates (Remel, Lenexa, algal biomass was applied (California Fish Kansas). These plates were incubated for and Game 2006). A 1m grid was placed at 48-72 hours at 35º C, followed by counting two separate locations within 10m of the of lactose-fermenting colonies. These established sampling site: where the largest colonies were then sub-plated in duplicate area of periphyton biomass was observed, onto MacConkey agar plates and incubated and where the least was observed. The at 42º C for 24 hours. This was done to percent of green, brown or orange algae identify thermo tolerant coliform species. bottom cover within the 1m grid was After the samples containing thermo tolerant estimated, photographed, and recorded. coliforms had been identified, further sub- Bacteria samples were 16 ml in volume and plating was done onto E. coli-specific media collected in Millipore total coliform count following standardized laboratory samplers (Millipore, Bedford, procedures. As one ml of water was filtered, Massachusetts). Samples were then kept any positive samples contained at least one cool for the remainder of the seven day CFU/ml, equivalent to 100 CFU/100ml. sampling trip and then refrigerated before Samples containing growth were scored as transport to the laboratory. positive and those without growth were scored as negative. No attempt was made to For suspended algae, a sample was quantify the number of colonies on each taken in order to measure chlorophyll-a sub-plate. concentration. 200 ml ambient surface water was filtered on a 25 mm GF/C following Chlorophyll-a standard methods after fixing with MgCl2 (Whatman, Cambridge UK) (American After being fixed in the field, the Public Health Association, 1998). samples of suspended algae were frozen Chlorophyll-a samples were fixed in 8ml upon arrival at the laboratory then analyzed tubes containing 100% ethanol, then using standard methods (American Public protected from light by wrapping in Health Association 1998). Filters were aluminum foil. Preservation of chlorophyll- banked, and analyzed several weeks later. At a through utilization of this technique has that time extracted chlorophyll was diluted been shown to retain >98% of chlorophyll at with an additional 8ml of 100% ethanol temperatures less than 22C for up to a week (total 16ml) and analyzed with a prior to freezing (Derlet, unpublished data). spectrophotometer comparing absorbance Air and water temperature, as well as before and after addition of 0.1 N HCl at altitude was also measured at each site. wavelengths of 750, 665, and 664 nm. The

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resulting absorbance was used to calculate sampling period of 6 days. This portion of chlorophyll-a levels following standardized the trail from Duck Pass to the JMT Junction methods (American Public Health featured highest frequency of manure, and Association, 1998). the trail above Duck Lake (Site 1) had very high occurrence of manure. Additionally at Data Analysis Duck Lake high concentrations of periphyton were observed (Figure 2.1). Site Potential correlations between along creek in Reds Meadow, North of JMT/ factors such as sample site location, water Duck Pass Trail Junction had large camping temperature, and altitude were examined site directly next to creek with large amount using multivariate logistic regression. of stock manure. This indicated that multiple Differences between the chlorophyll-a stock had been tied up overnight concentration of each site was analyzed with approximately 10 m from creek. JMT repeated measures ANOVA. Univariate portion south of JMT/ Duck Pass Trail analysis of coliform and E. coli prevalence junction to Florence Lake Trail junction for the three collection periods and site contained distinctly less manure than categories was performed using the Chi previous section. square test. Data is reported with standard deviation and 95% confidence intervals Purple Lake (Site 2) was off limits to where indicated. Results with p-values equal camping due to United States Forest Service to or less than 0.05 were considered to be (USFS) restoration project to improve water statistically significant. quality. However, it appeared backpackers were still camping at this site. Purple lake

had very high level of periphyton growth and substrate coverage (Figure 2.2). Results Virginia Lake (Site 3) had no evidence of periphyton growth in sampling A total of 20 lakes or streams were location (Figure 3.1). Warrior creek (site 5) studies. These sites were categorized by land had high degree of periphyton growth usage pattern as: 7 Wildlife, 5 Backpack, (Figure 2.3), though no evidence of pack and 8 Multiuse sites. Elevations ranged from animal manure was discovered. North Fork 2,100 m to 3,200 m. All sites were within Mono Creek (site 7) had no evidence of three km of the main trail. Locations of the periphyton growth (Figure 3.4); small sites sampled are shown in Table One. quantity of manure was located above sampling site (Mott Lake Trail) indicating Qualitative Field Observations infrequent use of trail by stock. Four A surprising biomass of fresh subsequent sites (sites 9-12) lacked evidence manure was noted along the entire study of any stock use, however JMT Side Creek length of the JMT. However the observed mile 86.6 (Site 9) contained high amount of frequency of pack animal traffic was periphyton while at sites 10-12 no limited. Along Duck Pass Trail large group periphyton was observed (Figure 3.3). of approximately 8 stock were passed on Hilgard Branch (Site 13) had high trail on the first day of the journey. This periphyton level, though Hilgard Branch was only sighting of actual stock during Trail was inspected for stock animal

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presence and none was found. This trail is were analyzed for chlorophyll as collecting popular with backpackers leaving the JMT equipment was damaged early in the to ascend Italy Pass. At Lake Beverly (Site expedition as a result of alpine weather 16, 1.1 miles from JMT) no evidence of conditions. Results were: Duck Ck 0.9, stock animals was found even though this Purple Lake 3.3, Virginia Lake 2.2 and historically sees heavy pack animal traffic; Squaw lake 10.7 mcg/L respectively. however this site had high periphyton levels Comparisons using ANOVA was performed (Figure 2.4). JMT Side Creek mile 95 (Site on the data collected from the 4 sites based 17) was classified as “pristine” and no on land use patterns. The collection numbers evidence of stock animals was observed, were to small to make statistical though some periphyton was found at this comparisons. site Coliforms and E. Coli Observation of backpackers along JMT indicated high degree of awareness in The prevalence of coliforms and E- respect to adherence of Wilderness area coli are depicted in Table 2. Overall, the guidelines for waste disposal, campsite highest prevalence of coliforms was found selection, fire regulations, etc. In terms of in Multiuse areas, where 5 of the 8 sites stock animals, frequency of stock animal (62%) exceeded the threshold of 100 waste and waste location indicate high CFU/100ml. This compares to an overall usage, and some cases of noncompliance prevalence of 0 of 5 (0%) in Wild areas, and with Wilderness regulations. 2 of 7 (28%) in Backpack sites. Comparison of Mixed use area coliform prevalence to Periphyton Wild was statistically significant (p<0.05). Comparison of Periphyton levels and Periphyton (attached and benthic Coliform prevalence among the land usage algae) was noted to be a significant problem categories showed a correlation of high in many lakes and streams. Figure 2 presents levels of periphyton with Mixed use areas. selected photos of the maximum algae Multivariate logistic regression analysis was density for 4 of the 20 sites sorted by performed for water temperature, altitude, wilderness land usage. Figure 3 depicts sampling sites. No significant association photos from 4 of the sites with the smallest between the finding of coliforms and water periphyton biomass. Maximum density temperature , altitude , Wild, Backpack, and measurements of periphyton ranged from 0 Mixed sites. E-coli >100CFU/100ml was to 90%, and minimums from 0 to 50% (table detected at only one mixed use site, Purple 4). Differences in attached algae biomass Lake, and at no other sites. were found when comparing mean maximal periphyton coverage (%) with usage categories: Pack animals; 59%, Backpack only; 42%, and Wildlife 10%. The Discussion difference between wildlife and pack The chief objective of this study was animals sites was statistically significant analyze and document the extent of attached (p<0.05). algae biomass in lakes and streams along the Chlorophyll-a concentration ranged central JMT between Yosemite and Kings between 0.9 to 10.7 mcg/L . Only 4 sites Canyon National Parks. In addition we

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aimed to compare any patterns in algae floating, but attached to various algae biomass with usage patterns of the species. In this instance Manure from JMT surrounding watershed among wildlife, pack animals has a 2 fold impact on water humans and pack animals, and prevalence of quality, first it provides large quantities of coliforms. Our data shows that Mixed-use Nitrates and Phosphates which stimulate the areas had the highest levels of attached algae algae growth, and secondly pack animals biomass. It confirms the prior years study of excrete huge numbers of fecal bacteria. this segment of trail as the prevalence of (Miettinen et al, 1997, Tao et al, 2007, Yers coliforms were elevated in mixed use areas et al, 2005). By one estimate, each 100 when compared with backpack or wildlife group of pack animals deposit 1 trillion watersheds. bacteria into the environment, some directly into lakes and streams. Visible benthic algae and aquatic plants occur first after the addition of Chlorophyll-a concentrations have nutriments, as one of the first macro been noted to have increased in larger lakes indicators of eutrophication (Horne and in the Sierra Nevada as a result of pollution Goldman 1994). If the process continues, and deposition of growth stimulating suspended algae levels also rise later in the compounds and elements (Winder et al, process as nutriment bioavailability 2007). Algae biomass surveys are important, increase. Our finding of large amounts of as water with higher algae levels also visible periphyton biomass in nearly all supports increased bacterial survival and Backpack and Mixed use sites shows that growth (Tao et al, 2007). Conditions which human activity is associated with a support elevated algae biomass also support significant increase in visible periphyton, the growth of blue green algae, which can when compared to the natural wild release several types of toxins harmful to watershed sites. This increase in humans and animals. For example in the eutrophication is concerning and threatens Swiss Alps, a report described 100 mountain the water supply (Conley 2009). Our finding cattle deaths, as a result of the release of of lower periphyton biomass levels in wild algae toxins, from blue green algae whose sites implies low levels of phytoplankton growth occurred from cattle manure and is not surprising. This may relate to the pollution into alpine water (Mez et al, 1997). their natural oligotrophic state in the To our knowledge, no extensive survey of absence of added nutriments from the algae biomass has been undertaken in the presence of humans or domesticated High Sierra Nevada wilderness areas. animals. Unfortunately we were able to obtain chlorophyll-a measurements from 4 sites, The finding that periphyton biomass and unable to have the power for statistical is directly proportional to coliform comparisons. However the values we prevalence is supports previous observations obtained from lakes are consistent with prior which associate pathogenic bacteria with measurements in the sierra, including the algae (Islam 2007). Pathogenic bacteria have central section of the JMT (Ursem 2009) higher nutriment demands than and Humphrey’s basin (Orlando and Knopp, environmental adapted bacteria. For 2005). The Tahoe Research Institute example, over 95% of Vibiro species of monitors Lake Tahoe frequently and surface bacteria in marine environments are not free

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chlorophyll-a in the center of the lake is 1.0 animals. Therefore, our findings in this mcg/L (Winder et al, 2008). study confirms the association of pack and stock animal presence with poorer water Coliforms prevalence provides quality. Increases in bacterial markers imply estimation for the risk for acquiring higher risk of waterborne disease to humans. pathogenic waterborne disease (American In addition to pathogenic forms of E. coli Association of Public Health, 1998). and Salmonella, pack and stock animals in Coliform bacteria have been used as the Sierra have a 3 to 6% prevalence of indicators of fecal contamination, including Giardia (Atwill, 2004, Johnson et al, 1997). for other organisms such as Giardia, in Although this number may seen small, water across the United States. In wilderness according to a study conducted in Yosemite, areas, coliforms may originate from one or a each infected animal excretes over combination of sources including 1) wild 10,000,000 cysts into the environment each animals endemic to the area; 2) humans day, placing wilderness hikers at risk if visiting during daylight; 3) backpackers who water is untreated (Atwill, 2004). camp overnight; 4) stock or pack animals, such as horses and mules; and 5) cattle or sheep grazing. Coliform pollution of wilderness areas by humans may occur Limitations through inadequate burial and disposal of Many unforeseen obstacles were fecal material. In addition, bathing or encountered during the course of this swimming in lakes may also result in project. The aforementioned loss of microbial pollution (Blostein, 1991). Pack chlorophyll-a filters presented a problem. animals pollute by deposition of manure Overall numbers of samples for coliforms either directly into lakes and streams or were small, although consistent with prior indirectly by deposition of manure onto studies. Estimation of periphyton biomass is trails or meadows, and these animals have visual, and although photographically been documented to import pathogenic archived, may be subject to different microorganisms into the Sierra wilderness interpretations from various individuals. (Yers et al, 2005, Atwill 2004). This manure may be washed into waterways by either summer storms or annual snowmelt (Gurber et al, 2006, Durkee 2008, unpublished data) Our findings are consistent with prior studies in the Sierra showing the highest Conclusion prevalence of coliforms occur in areas used A high biomass of periphyton was found in by domesticated animals (Derlet et al, 2008). lakes and streams adjacent to areas mixed- The lower prevalence of coliforms in Wild use areas those areas use by stock together areas and higher prevalence in mixed use with backpackers. In addition the and Backpack sites suggest a significant prevalence of coliforms was highest in contribution from humans. Additionally, the mixed use areas. In contrast, sites used only Backpack sites were noted to have a similar by backpackers had fewer coliforms and density of campsites as the mixed use sites, much less periphyton biomass. Wild sites suggesting increased coliform prevalence at showed little periphyton biomass. Taken mixed use sites is from the impact of pack together this study provides evidence that

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pack and stock animals traffic are major Derlet R.W., Ger K.A., Richards J.R, contributors to the eutrophication of lakes Carlson J.R. (2008). Risk factors for and streams in the Sierra Nevada along the coliform bacteria in backcountry lakes and JMT. streams in the Sierra Nevada Mountains: A 5-Year Study. Wilder Environ Med. 19:82- 90.

References: Goldman C.R. (2000). Four decades of change in two sub Alpine lakes. Verh Internat Verein Limnol. 27:7-26. American Public Health Association (1998). Standard methods for examination of water. Guber A.K., Shelton D.R., Pachepsky Y.A., 20th Ed. United Book Press Inc, Baltimore; Sadeghi A.M., Sikora L.J. (2006). Rainfall- Section 9; pp. 1-140. induced release of fecal coliforms and other manure constituents: Comparison and Atwill R. (2003). Yosemite pack stock and modeling. Appl Environ Microbiol. microbial water quality project. In: National 72:7531-7539. Park Investigator Reporting System. United States National Park Service. Washington, Harvey S., Greenwood J.R., Pickett M.J., DC. Mah R.A. (1976). Recovery of Yersinia enterocolitica from streams and lakes of Blostein J. (1991). Shigellosis from California. Appl Environ Microbiol. 32:352- swimming in a park pond in Michigan. 354. Public Health Rep. 106:317-322. Horne A. and Goldman C. (1994). Streams California State Water Resources Board. and rivers. In: Limnology. 2nd Ed. (2002). Water quality enforcement policy. McGraw-Hill, New York; pp. 356-383. Sacramento, CA Islam MS, Jahid MIK, Rahman MM. (2007). Carle D. (2004). Introduction to water in Biofilm acts as a microenvironment for California. University of California Press, Plankton associated Vibrio cholerae in Berkeley, CA. pp. 1-32. aquatic environments of Bangladseh. Microbiol. Immunol.,51;369-379. Conley DJ, Paerl HW, Howarth RW, et al, (2009) Controlling eutrophication: Nitrogen Jasson M., Bergstrom A.K., Lymer D., and Phosphorus. Science 323;1014-1015. Verde K., Karlsson J. (2006). Bacterioplankton growth and nutrient use efficiencies under variable organic carbon Derlet R.W. and Carlson J.R. (2006). and inorganic phosphorus rations. Microb Coliform bacteria in Sierra Nevada Ecol. 52:358-364. wilderness lakes and streams: What is the impact of backpackers, pack animals, and Johnson E., Atwill E.R., Kalush F.J. (1997). cattle? Wilder Environ Med. 17:15-20. The prevalence of shedding of cryptosporidium and giardia based on single

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fecal sample collection from each of 91 horses used for backcountry recreation. J Yers H.L., Cabrera M.L., Matthews M.K., et Vet Diagn Invest. 9:56-60. al. (2005). Phosphorus, sediment and Escherichia coli loads in unfenced streams Lowe D. and Lowe R. (1982). In: The John of the Georgia Piedmont, USA. J Environ Muir Trail. Caxton Publications, Cadwell. Qual. 34:2290-2300. pp. 1-26. Winder M., Reuter J.E., Schladow S.G. Mez K., Beattie K.A., Codd G.A., et al. (2008). Lake warming favors small sized (1997). Identification of a microcystin in planktonic diatom species. Proc R Soc B: benthic cyanobacteria linked to cattle deaths doi:10.1098/rspb.2008.1200 published on alpine pastures in Switzerland. Eur J online. Phycol. 32:111-117.

Miettinen I.T., Vartiainen T., Martikainen P.J. (1997). Phosphorus and bacterial growth in drinking water. Appl Environ Microbiol. 63:3242-3245.

Moore J.G. (2000). Exploring the highest Sierra. Stanford University Press, Stanford. pp. 1-86.

Orlando S. and Knapp R.A. (2005). Nutrient recycling by fish versus zooplankton grazing as drivers of trophic cascade in alpine lakes. Limol Oceanogr. 50:2032-2042.

Tao W., Hall K.J., Ramey W. (2007). Effects of influent strength on microorganisms in surface flow mesocosm wetlands. Water Res. 41:4557-4565.

Ursem C, Evans CS, Ger KA, Richards JR, Derlet RW. (2009). Surface Water Quality along the Central John Muir Trail in the Sierra Nevada Mountains: Coliforms and Algae. J High Altitude Medicine and Biology. 10: 349-355.

Wenk E. and Morey K. (2007). The John Muir Trail: Guide to America’s most famous trail. The Wilderness Press, Berkeley. pp. 1- 280.

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Figure 1.

Central John M uir Trail California, USA

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Figure 2: Photos from 4 sites with the largest biomass of periphyton:

Fig 2.1‐Duck Lake

3Fig ‐ 2. Warrior Creek

Fig 2.2 ‐ Purple Lake

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Fig 2.4 ‐ Lou Beverly Lake

Figure 3: Representative photos from 4 sites with the least visible periphyton:

Fig 3.1 ‐ Lake Virginia Fig 3.2 ‐ Silver Pass Creek

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Fig 3.3 ‐ JMT Side Ck mile 87 Fig 3.4 ‐ North Fork Mono Creek

Table 1. Specific site location by watershed category (Elevation above sea level in meters)

Wildlife Backpack Multiuse

JMT Side Creek mile 86.6 (2,780) by Aspens Squaw Lake (3,133) Duck Creek (3,072)

JMT Side Creek mile 86.9 (2,780) North side Warier Lake (3,188) Purple Lake (3,026) of Recess Peak

JMT Side Creek mile 87 (2,780) North Fork Mono Creek above JMT (2,740) Virginia Lake (3,151)

JMT Side Creek mile 88 (2,780) (South side Creek South of Crater Meadow (2,658) Fish Creek crossing (2,804) of Recess peak)

JMT Side Creek mile 95 (3,267) just South of Hilgard Branch (2,850) Silver Pass Creek cross (2,926) Seldon Pass

Orchid Lake Outflow Stream (2,920) Lou Beverly Lake (3,072)

Senger Creek (2,975) Marie Lake, Muir Wilderness (3,216)

Sally Keys Lake (3,121)

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Table 2. Coliform prevalence and observed Periphyton Biomass by watershed category. Data presented as prevalence of Coliforms (%), and Periphyton benthic coverage (%).

Coliforms E-Coli Periphyton

Wild 0 0 10

Backpack 28 0 42

Mixed-use 63 13 59

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